If i did the calculations and the math right, it should be something like this:
Current situation for buying 1 btc:
price at www.bitstamp.net : $318.93
fee: 0.44% = $1.7
total: $317.23
Current situation for selling1 btc:
price at www.portbitcoin.com : $328.95
fee: $1
bonus code BITRIP293 boost: 5% = $16.4
total: $342.35
Current situation for buying 1 btc:
price at www.bitstamp.net : $318.93
fee: 0.44% = $1.7
total: $317.23
Current situation for selling1 btc:
price at www.portbitcoin.com : $328.95
fee: $1
bonus code BITRIP293 boost: 5% = $16.4
total: $342.35
I think you forgot your calculator and don't know how works fees
For first operation (buy), when you buy BTC with FIAT ($), fees are added to total cost, not deducted like you did.
For second operation (sell), your calcul is wrong. This is the right calcul (328.95-1+16.4=344.35).
In this case, we'll deduce fees from $ amount that we'll receive.
And last point, it's better to do calcul without any "bonus code" with her special condition...
There are lots of opportunity without need a coupon
Please, edit your post with right calcul and right fees deduction